1. Field of the Invention
This invention relates to a method for the production of an alcohol and/or a ketone from a saturated hydrocarbon and an epoxide from an unsaturated hydrocarbon by the oxidation with oxygen of the hydrocarbon using of a gold-titanium dioxide-containing solid catalyst in the presence of hydrogen.
2. Description of the Prior Art
The method for converting a hydrocarbon into a compound containing oxygen by the use of oxygen is a very advantageous technique and has provided the modern chemical industry with numerous benefits. It has been held, however, that, with a few exceptions, direct production of an alcohol and a ketone from a saturated hydrocarbon and an epoxide from an unsaturated hydrocarbon is generally difficult. The only industrial-scale application of the technique for converting a saturated hydrocarbon into an alcohol and a ketone by the use of molecular oxygen as an oxidizing agent, for example, has been in the production of cyclohexanol and cyclohexanone from cyclohexane as the starting material. While the technique for conversing an unsaturated hydrocarbon into an epoxide has been put to use on an industrial scale for the production of ethylene oxide from ethylene, the production of epoxides from other unsaturated hydrocarbons, such as the synthesis of propylene oxide from propylene, is generally difficult to attain.
Previously reported techniques for the conversion of a saturated hydrocarbon into an alcohol and a ketone and the conversion of an unsaturated hydrocarbon into an epoxide by oxidation with molecular oxygen include the following problems.
First, the gaseous-phase reaction by the use of molecular oxygen usually requires a reaction temperature of not lower than 200.degree. C. and is therefore not readily applicable to the production of an alcohol, a ketone or an epoxide from a hydrocarbon with high selectivity. This is mainly because it is extremely difficult to optimize the reactivities of oxygen species, especially: 1) when the hydrocarbon is a saturated hydrocarbon, the alcohol or ketone which is the partial oxidation is further oxidized and 2) when the hydrocarbon is unsaturated hydrocarbon, an oxide other than desired one is obtainable (e.g. acrolein is produced instead of an epoxide when the hydrocarbon is propylene).
A number of catalysts recently proposed for increasing the efficiency of the oxidation reaction of hydrocarbons, although low in activity, exhibit high selectivity by activating oxygen in the presence of a reducing agent and effecting a reaction of the enzymatic type capable of inducing in vivo addition of one oxygen atom under relatively mild conditions.
When the Gif catalyst system (reported in J. Chem. Soc. Chem. Commun., 1983, 731, for example), a well-known catalyst system that functions similarly to the one oxygen-atom addition enzyme, is used, for example, the compound mentioned above is produced with high selectivity by oxidizing a saturated hydrocarbon with oxygen by the use of an iron type catalyst in such a proton-donating solvent as acetic acid in the presence of such an electron-donating agent or reducing agent as zinc powder. The use of this catalyst is, however, not practicable, because the production efficiency is extremely low and the reaction system is complicated.
Successful epoxidation of an unsaturated hydrocarbon by the use of an alcohol or an aldehyde as an electron-donating agent have been reported (in Bull. Chem. Soc. Jpn., 1992, 64, 2513, for example). Since the alcohol or aldehyde is oxidized together with the unsaturated hydrocarbon, however, this method has many problems yet to be solved.
Attempts are being made to implement the epoxidation by the use of hydrogen as an inexpensive reducing agent. According to a report in J. Chem. Soc. Chem. Commun., 1992, 1446-1447, the oxidation of a hydrocarbon (hexane in this case) containing a proton source such as hydrochloric acid effected by suspending in the hydrocarbon a catalyst of Pd deposited on titanosilicate and bubbling hydrogen and oxygen through the hydrocarbon produces the corresponding alcohol and ketone with high selectivity. J. Amer. Chem. Soc., 1987, 109, 2837-2839 reports that similar results are obtained when a similar procedure is carried out on hexanes and octanes by the use of a catalyst consisting of Pd and Fe deposited on zeolite. These methods are, however, not practicable in terms of the reaction rate because hydrogen peroxide is produced on the Pd to oxidize a hydrocarbon and because the reaction should be carried out in a liquid phase.
Some of the methods which use a reducing agent as described above are indeed capable of obtaining results satisfactory in terms of selectivity. They are nevertheless unfit for actual use because their production efficiencies are low and their reaction systems are complicated.
A need therefore exists for the development of a method for producing an alcohol, a ketone, and an epoxide at a high selectivity with a high yield by the oxidation of a saturated or an unsaturated hydrocarbon.
The inventors continued a study with a view to providing such a method and accomplished this invention as a result.